The invention relates to the technical field of motor vehicle gearboxes.
To be more specific, the invention relates to a device for detecting the neutral position of a control lever and can be used to particular advantage in a mechanical gearbox.
In a manner fully understood by those skilled in the art, the lever, or some other actuator member, is generally mounted, such as to be capable of angular movement, in a carrier housing secured to the interior of the vehicle. The lever is arranged to control selecting and shifting the gears.
Various solutions have been put forward for detecting the position of the lever so as to get to know the movements thereof and, consequently, its exact position in space. For example, document FR 2,930,309, which is also owned by the applicant of the present invention, relates to a device suitable for providing accurate information as to the various positions and directions of movement of the control lever.
To this end, a Hall effect sensor is mounted onto a fixed portion of the carrier housing in which the lever is articulated, opposite a magnet carried by said lever, in order to show the various movements and positions taken up by the lever, along three perpendicular axes x, y, z.
Starting from this basic concept, the problem the invention sets out to resolve is that of being able, in a straightforward and effective manner, to detect the position of the lever, particularly at the neutral point, something which proves important for vehicles fitted with systems suitable for cutting off the power supply to the drive motor when the vehicle is stopped for a preset length of time, so as to allow the vehicle to start again when the driver presses the accelerator pedal.
The use of a gearbox position sensor emitting an output signal representing the position of the neutral point is treated as known in document WO 2008/155289. To be more specific, the purpose of this document is to continually verify the integrity of the emitted output signal, whatever type of fault may occur.
To meet this objective, said document proposes combining the position sensor with a signal processing unit comprising an analogue-to-digital converter suitable for converting the analogue signal into a digital output signal in order to provide pre-specified periodic data corresponding to the position of the neutral point when two conditions are satisfied at the same time, namely that a magnet is in the neutral point position and the sensor is in a normal state of operation.
Based on this prior art, and in particular supplementary to the teaching in document FR 2,930,309, it seemed important to specify the nature and positioning of the means suitable for detecting the movements of the lever, so as to be completely separate from the movement of the lever corresponding to gear selection, which means that the neutral point can be detected straightforwardly, in a secure and effective manner.